When a person stands up after sitting or lying down, blood normally pools in the legs because of gravity. The body then works to push blood upward to supply the brain with oxygen.
If the body is unable to do this sufficiently, blood pressure falls, which may lead to symptoms, such as dizziness, blurred visions, or fainting.
What is orthostatic hypotension?
Low blood pressure is a symptom of orthostatic hypotension.
Hypotension, or low blood pressure, occurs when the blood pressure in the arteries falls below normal levels.
The heart pumps blood around the body through blood vessels. These tubular structures include arteries, veins, and capillaries. Blood pressure is a measure of the force of the blood on the walls of the arteries as it pumps through them.
Blood pressure is measured in millimeters of mercury (mmHg) and has two figures:
- Systolic pressure: the pressure when the ventricles of the heart squeeze and propel blood into the arteries.
- Diastolic pressure: the pressure measured between heartbeats when the ventricles relax. This is the time that the heart receives its oxygenated blood.
A systolic blood pressure reading of 120 mmHg and a diastolic blood pressure of 80mmHg or 120/80 are considered normal. A person with a reading of 90/60 mmHg or lower is considered to have hypotension or low blood pressure.
People who have orthostatic hypotension often experience a drop in blood pressure of about 20/10 mmHg within 3 minutes of standing.
Low blood pressure does not usually require treatment. If a person experiences regular symptoms of orthostatic hypotension, however, they should see a doctor.
Orthostatic hypotension is common among people who are 65 or older because the body's ability to react to drops in blood pressure can slow down as a person ages.
Figures cited in research by the National Center for Biotechnology Information estimate that orthostatic hypotension is prevalent in around 18 percent of men and women aged 65 or older in the United States.
The same study noted that cases of orthostatic hypotension among the elderly account for 35 percent of hospital admissions in the U.S.
Loss of fluid within the blood vessels is the most common cause of symptoms linked to orthostatic hypotension. This could be due to dehydration brought about by diarrhea, vomiting, and the use of medication, such as diuretics or water pills. This medication helps the body get rid of excess water and salt through urine.
Loss of blood, anemia, and other conditions that result in a lower red blood count are also likely causes. When there are fewer red blood cells available to carry oxygen in the bloodstream, dizziness and light-headedness may occur.
Some medications, such as beta-blockers and antidepressants, can also trigger symptoms linked to orthostatic hypotension. Working or exercising in hot weather or being bedridden for a prolonged period can also lead to these symptoms.
Parkinson's disease, pregnancy, and heart conditions such as irregular heart rhythms and valve disease are also known to cause symptoms connected to orthostatic hypotension.
Dizziness, blurred vision, and feeling faint may be symptoms of orthostatic hypotension.
The symptoms of orthostatic hypotension include:
- blurred vision
These symptoms usually go away as the body slowly adjusts to an upright position, or after sitting or lying down for several minutes.
Anyone who experiences any of these conditions regularly should seek medical advice immediately.
A common complication of orthostatic hypotension is falling over as a result of losing consciousness, which could cause serious injuries.
The symptoms could also mask more serious conditions. These include cardiovascular diseases, such as heart failure and heart rhythm problems.
The sudden drops in blood pressure caused by orthostatic hypotension are a risk factor for strokes because of the reduced blood supply to the brain.
If someone experiences any of the above symptoms, their doctor will look into their medical history. If needed, the doctor will then conduct tests to find out if an underlying condition or illness is causing the symptoms.
For example, if a particular medication is causing the blood pressure to drop, the doctor may adjust the dosage or recommend a switch to another drug.
A head-up tilt table test will look at how a person's blood pressure reacts to changes in their body's position. During this test, a person lies on a table that is slowly tilted upward.
Blood tests can show whether someone has low blood sugar or a low number of red blood cells, which are both signs of low blood pressure.
An electrocardiogram (ECG or EKG), which monitors the heart's electrical signals, can uncover irregularities in heart rhythm and problems with blood and oxygen supply to the heart.
An ultrasound of the heart, or echocardiogram, assesses the heart valves using sound waves and could uncover underlying disorders.
A stress test can be conducted where a doctor monitors the heart while the person is exercising or after being given medication.
Treatment and prevention
There are several ways of managing or preventing orthostatic hypotension, most of which do not involve the use of medication.
- Keep hydrated by drinking plenty of fluids. Fluids lost from diarrhea or vomiting should be replaced immediately. Avoid or limit alcohol intake because alcohol can worsen orthostatic hypotension.
- Use more salt in meals. However, consult a doctor first as too much salt in the diet can increase blood pressure.
- Avoid strenuous activity during hot weather.
- When getting out of bed, sit on the edge of the bed for a minute before standing.
- Sleep with the head of your bed slightly elevated.
- Compression stockings can promote circulation and help prevent fluid from pooling in the legs.
Severe cases of orthostatic hypotension can be treated with drugs to raise blood pressure.